Wednesday, March 22, 2017

More on life

God is alive, angels are alive, people are alive, dogs are alive, worms are alive and trees are alive. What is it that makes them all be alive, while the Milky Way, the Sun, Etna, a car, a Roomba, and an electron are not? I raised a version of this question recently, and since then have had discussions about it with a number of our graduate students, most extensively with Alli Thornton and Hilary Yancey, to whom I am very grateful.

We could say that they are all alive in an analogical sense. But that doesn’t solve the problem, but simply puts a constraint on the shape of a solution. For to solve the problem, we still have to say something about how this particular analogy works.

Here is the best answer I have right now, but it still has some difficulties I will discuss:

  • A living thing is one that can act in pursuit of its own ends.

This indeed covers God, angels, people, dogs, worms and trees. Moreover, it produces a gradation of life in respect of the degree and quality with which the thing can act in pursuit of its own ends and the degree of ownership the thing has over its ends. For instance, God is omnipotent and perfectly rational, and he is his own end, so he is most fully alive. All the living creatures, on the other hand, have ultimate ends imposed on them by their nature, to the realization of which end their activity are ordered. However, angels and people additionally make a rational choice of ways to realize their ultimate ends, adopting which ways involves setting themselves intermediate ends. Higher non-human animals like dogs do something that approximates this. Moreover, angels, people and dogs have a wide variety of ways of pursuing that end. On the other hand, trees only pursue a limited variety of ends with a limited variety of means.

A bonus of this definition is that we get the conclusion, which seems intuitively correct, that anything that thinks is alive. For thinking is an end-directed activity—it is directed at action and/or truth. So if we ever make an artificial intelligence system that really thinks, it will be alive.

The Milky Way, the Sun, Mount Etna, a car and a Roomba do not pursue their own ends, I think, if only because they are not substances, and only substances own their ends.

But electrons… This is what troubles me. I think that the fundamental constituents of physical reality, be they particles or fields, are substances. And I think all substances have a teleology, and hence have an end. The distinction I would like to be able to make, however, is between activity in pursuit of an end and teleological activity more generally. Electrons in their characteristic activity are acting teleologically. But their action is not in pursuit of an end. Rather their end is simply to engage in this very activity and nothing more. The activity is teleological, but it does not pursue a telos.

But what if it turns out that electrons do genuinely act in pursuit of an end? Then, perhaps, we will have learned that electrons are a very primitive form of life.

What about God, given divine simplicity, though? God = God’s telos = God’s activity. Well, I think that even if God’s activity is identical with God’s telos, one can make a conceptual distinction that allows one to say that God acts for the sake of that telos, a distinction that perhaps is not there in the case of the electron.

As you can see, I am still not very happy with the account. But it’s the best I have right now.


bethyada said...

Living things have DNA (excluding angels etc). Use of DNA is manipulation of information. Angels can manipulate information without DNA (as far as we know they do not have DNA). So manipulation of information seems to be somewhat definitional of life. But other actions are manipulation of information, eg. smart phones.

Your definition works except it may include non living things such as electrons. Combining the definitions

*A living thing is one that can manipulate information in pursuit of its own ends.

I guess I am uncertain how we can include pursuit of own ends unconsciously because if a plant can do this so can a computer. The difference here is reproduction.

Jo F said...

What makes the ends of something "its own"? It'd be helpful to have a definition of this, because when we consider living things that cannot be conscious of their own ends this definition of life begins to sound like it ascribes a degree of intentionality that those living things may not actually have. I.e. One may ask, "does a plant, as it nourishes itself, pursue the end of its own well being--or is the plant merely a collection of unconscious substances that have been shaped by some evolutionary mechanism for enough time to perform the tasks that sustain the growth and existence of a certain set of particles which die off in the service of another set of particles on and on until the entire set is transformed into another set of particles that does not perform these activities (what we normally understand as "death" and "organic decay into inorganic materials")?

Jo F said...

In response to myself...

I suppose that the particles' performing of tasks which sustain the existence of a total set of particles and themselves is what makes the collection of that set of particles "living".

Alexander R Pruss said...


This is promising, but I fear that by computational accounts of information, an avalanche is computing some informational stuff.


That's a great question. I don't know what the ownedness consists in. But then every definition has to bottom out in something one can't define. Yeah, that's a cop out.

bethyada said...

Thanks, but is it really. If we model an avalanche we are computing but that is not the same as what an avalanche is doing. What an avalanche is doing is just following the pathway of how the universe exists. It doesn't compute anything.

I would claim that the amount of information required to describe a state is distinct from any amount of information processing by anything to bring about that state.